Seat belts may enhance occupant protection in a vehicle. For example, in impact events and vehicle rollovers, seat belts can function to reduce secondary impacts, to keep occupants correctly positioned for secondary restraint systems (e.g., airbags), and to assist in preventing occupants from being ejected from the vehicle.
Impact events and vehicle rollovers may result in occupants sliding out from underneath the seatbelt. For example, forces from an impact can propel the occupant under the seatbelt, a phenomena sometimes referred to as submarining. When submarining occurs, safety benefits that may otherwise be provided by seat belts can be lost.